Valve arrangement

ABSTRACT

An electromagnetic valve arrangement with a valve element having least one part disposed in a valve chamber defined by a valve insert in the region of a valve seat. An end facing away from the valve chamber of the valve element is operatively connected to an armature and end face of the armature facing toward the valve insert and/or an end face of the valve insert facing toward the end face of the armature is embodied with a surface profile such that a flow cross section, defined by the opposed end faces varies at least regionally in the radial direction and/or in the circumferential direction of the armature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an improved electromagnetically actuated valvearrangement of the type useful, for example, in brake systems for motorvehicles.

2. Description of the Prior Art

From German Patent Disclosure DE 100 36 576 A1, an electromagneticallyactuatable valve arrangement which is usable particularly in hydraulicbrake systems of motor vehicles is known. The valve arrangement includesa valve insert embodied with a longitudinal bore and solidly connectedto a valve dome. Disposed in the valve dome is an armature,longitudinally movable in the axial direction of the valve arrangement,that is operatively connected to a valve tappet guided longitudinallymovably, likewise in the axial direction, in the valve insert. Theoperative connection between the armature and the valve tappet or thevalve element is such that an armature motion in the closing directionof a valve seat is transmitted to the valve tappet embodied with aclosing member, so that a seat valve is closed upon contact of theclosing member with a valve seat.

The valve tappet is guided with slight radial play in the longitudinalbore of the valve insert and is provided on its jacket side with atleast two conduits, separate from one another. A valve chambercontaining the seat valve of the valve arrangement communicatesfluidically through the conduits with voids inside the valve dome, sothat residual air in the valve dome can be positively displaced via theconduits.

The valve arrangement, in the currentless state, is furthermore kept inthe opened state by a spring assembly or a restoring spring; the springassembly, embodied as a compression spring, is built into the valvechamber. This disposition of the spring assembly assures simple assemblyof the valve arrangement.

By actuation of the valve arrangement which is open when withoutcurrent, the armature is displaced with the valve element. Between thevoids, which are defined on the end facing away from the valve elementby the valve dome and the armature and in the contact region of thearmature on the valve element by the armature, the valve element, thevalve dome, and the valve insert, a volumetric and pressure compensationtakes place, which in operation of the valve arrangement is associatedwith a flow of the operating fluid located in the interior of the valvearrangement.

The fluid flow, in unfavorable operating states of the valvearrangement, in the region of the end faces, facing toward one another,of the armature and of the valve insert, leads to an unwanted motion ofthe armature and thus also of the valve element in the direction of thevalve seat, which is due to an effect of the hydrodynamic paradox thatoccurs between the end faces of the armature and of the valve insert.

This unwanted motion of the armature and of the valve element in thedirection of the valve seat leads, in operation of the valvearrangement, to an uncontrollable change in location of the armature andalso of the valve element, which under some circumstances leads to anunwanted change in the flow cross section of the valve arrangement inthe region of the valve seat, and as a result an open-and closed-loopcontrol characteristic of the valve arrangement can be verified orreplicated only with difficulty.

SUMMARY AND ADVANTAGES OF THE INVENTION

In the valve arrangement of the invention, which is embodied having avalve element is disposed longitudinally movably in a valve insert andcooperating with a valve seat embodied in a valve body, which valveelement in the installed position of the spring assembly is acted uponwith a force component acting in the opening direction of the valve seatand can be actuated in the closing direction of the valve seat via anelectromagnetic actuator, where at least part of the valve element isdisposed in a valve chamber defined by a valve insert in the region ofthe valve seat, and an end, facing away from the valve chamber, of thevalve element is operatively connected to an armature, an unwanted anduncontrollable change in location of the armature and of the valveelement relative to the valve seat in the operation of the valvearrangement is avoided in a simple way.

This is attained by providing that an end face of the armature facingtoward the valve chamber, and/or an end face of the valve insert facingtoward the end face of the armature is embodied with a surface profilesuch that a flow cross section, defined by the end faces, varies atleast regionally in the radial direction and/or in the circumferentialdirection of the armature. This means that the end face of the armatureand/or the end face of the valve insert is altered, in comparison to thevalve arrangements known from prior art, in such a way that no uniformspacing exists between the end faces of the armature and of the valveinsert over the full armature diameter, and thus the foundations for theoccurrence of effects of the hydrodynamic paradox do not exist. Thusadvantageously neither the position of the armature nor the position ofthe valve element relative to the valve seat is changed by unwantedeffects in the interior of the valve arrangement, and as a result thepositions of the armature and of the valve insert are controllable tothe extent required for perfect functioning of the valve arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and advantageous refinements of the subject of theinvention will become apparent from the description contained hereinbelow, taken in conjunction with the drawings, in which:

FIG. 1 is a schematic longitudinal section through a valve arrangementembodied according to the invention;

FIG. 2 is a schematic three-dimensional individual illustration of anarmature of the valve arrangement of FIG. 1; and

FIG. 3 is an alternative design of an armature of the valve arrangementof FIG. 1, in a view corresponding to FIG. 2.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

In FIG. 1, the valve arrangement 1 is embodied with a valve element 5that is disposed longitudinally movably in a valve insert 2 and thatcooperates with a valve seat 4 embodied in a valve body. In theinstalled position, the valve element 5 is acted upon by a springassembly 6 with a force component acting in the opening direction of thevalve seat 4. The valve element 5 is furthermore actuated in the closingdirection of the valve seat 4 via an electromagnetic actuator, not shownin detail.

A region of the valve element 5 oriented toward the valve seat 4 isdisposed in a valve chamber 7, which is defined by the valve insert 2 inthe region of the valve seat; the dimensions of this chamber are shownas a rectangle drawn in dot-dashed lines in FIG. 1. The region of thevalve element 5 disposed in the valve chamber 7 has a frustoconicalregion 5A, a first cylindrical region 5B adjoining the frustoconicalregion 5A, and a third conical-caplike region 5C in turn adjoining thefirst cylindrical region 5B. The conical-caplike region 5C of the valveelement 5 cooperates with the conically embodied valve seat 4 in such away that upon contact of the valve element 5 on the valve seat 4, asealing action prevails of a kind such that an inflow region 8 of thevalve chamber 7 and an outflow region 9 of the valve chamber 7 aredisconnected from one another when the valve seat 4 is closed.

The valve arrangement 1 substantially comprises the hydraulic module 1A,shown in FIG. 1, and an electrical module, slipped onto the hydraulicmodule 1A and not further shown, which is embodied in a manner known perse with a coil, an electric winding, and a yoke ring disk, in order toactuate an armature 10 of the hydraulic module 1A, as a so-calledelectromagnetic actuator, in the closing direction of the valve seat 4counter to the spring force of the spring assembly 6.

In the present case, the armature 10 is guided longitudinallydisplaceably in a valve dome 11 solidly connected to the valve insert 2,and together with the valve dome 11 it defines a plurality of conduits12A, which connects a valve dead space 13, defined between the valvedome 11 and the end of the armature facing away from the valve seat 4,to the valve chamber 7 via tappet grooves 12B of the valve element 5.

The valve element 5, in the currentless state of the valve arrangement1, is thrust away from the valve seat 4 in the direction of the valvedead space 13 by the spring force of the spring assembly 6, which isbraced in the axial direction on the end face 15, toward the valveelement 5, of the valve body 3, so that the armature 10 is moved awayfrom the valve insert 2 and is pressed against the valve dome 11 in theregion of the valve dead space 13 and rests on the valve dome. In thisposition of both the valve element 5 and the armature 10, the valve seat4 is uncovered by the valve element 5, or the conical-caplike region 5Cof the valve element 5, and the inflow region 8 communicates with theoutflow region 9.

In this state of the valve arrangement 1, the operating medium can bedelivered, via the valve arrangement 1, or in other words beginning atthe inflow region 8 of the valve chamber 7 to the outflow region 9 ofthe valve arrangement via the valve seat 4, and to a region,communicating with the outflow region 9, of an ABS (anti-lock brakesystem), TCS (traction control system), or ESP (electronic stabilityprogram) system.

To close the valve seat 4, the electrical module, slipped into a knownmanner onto the valve dome 11, of the valve arrangement 1 is suppliedwith current such that the electrical module generates anelectromagnetic force, which displaces the armature 10 from its positionshown in FIG. 1 in the direction of the valve seat 4 and presses theconical-caplike region 5C of the valve element 5 sealingly against thevalve seat 4 of the valve body 3. In this last-described state of thevalve arrangement 1, the inflow region 8 is disconnected from theoutflow region 9, and no operating medium can be supplied via the valvearrangement 1, if a positive pressure drop exists between the inflowregion 8 and the outflow region 9. Here, in the interior of the valvearrangement 1, a positive pressure drop exists between the inflow region8 and the outflow region 9 if the pressure in the inflow region 8 of thevalve chamber 7 is greater than the pressure in the outflow region 9 ofthe valve arrangement 1.

This is due to the fact that the inflow region 8, when there is apositive pressure drop compared to the outflow region 9 and when thevalve seat 4 is closed, is disconnected from the outflow region 9 by acheck valve 14; at a negative pressure drop, or in other words in thepresence of a pressure in the outflow region 9 that is greater than thepressure in the inflow region 8, the check valve 14 is open.

In the valve arrangement 1 shown in FIG. 1, the spring assembly 6 isdisposed with its region toward the valve body 3 in the valve chamber 7,through which, when the valve seat 4 is open, fluid or operatingmedium-or brake fluid in the case where the valve arrangement 1 is usedin an ABS system of a motor vehicle-flows from the inflow region 8 inthe direction of the outflow region 9.

In FIG. 2, the armature 10 is shown in a three-dimensional view, inwhich an end face 15 of the armature 10, facing toward the valve element5, is shown in further detail. The end face 15 of the armature 10 isembodied with a plurality of circular channels 15A through 15E disposedconcentrically to one another, so that a spacing between the end face 15of the armature 10 and an end face 16 of the valve insert 2, facingtoward the end face 15 of the armature 10, varies at least in someregions in the radial direction in such a way that the conditionsrequired, when there is a flow between the valve dead space 14 and thevalve chamber 7 in the region between the armature 10 and the valveinsert 2, for the occurrence of an effect of the hydrodynamic paradox nolonger exists.

In FIG. 3, a refinement of the armature 10 shown in FIG. 2 is shown; inthe region of its end face 15, it is embodied with a so-called radialgroove 17, which is based on essentially the same mode of operation asthe aforementioned circular channels 15A through 15E.

As an alternative to the exemplary embodiment of the subject of theinvention shown in FIG. 2 and FIG. 3, the end face of the armatureand/or the end face, facing toward the armature, of the valve insert mayeach be embodied with arbitrary geometries, which lend the end face ofthe armature and/or the end face of the valve insert a surface profilesuch that there is no uniform spacing between the end faces.

Here, the circular channels 15A through 15E and the radial groove 17 areall embodied with a substantially semicircular profile in cross section;it is understood to be within the judgment of one skilled in the art toembody both the channels and the radial groove, depending on aparticular application in question, with other suitable cross-sectionalprofiles.

The possibility furthermore exists of altering the end face of thearmature and/or the end face, toward the armature, of the valve insertmicroscopically by means of other suitable surface treatment processes,compared to a substantially plane, smooth surface, in such a way thatthe effect of the hydrodynamic paradox is avoided.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the claims.

1. In a valve arrangement having a valve element, which is disposedlongitudinally movably in a valve insert and cooperates with a valveseat embodied in a valve body, which valve element in the installedposition is acted upon, by a spring assembly disposed between the valvebody and the valve insert, with a force component acting in the openingdirection of the valve seat and is actuatable in the closing directionof the valve seat via an electromagnetic actuator, the spring assemblyand at least one part of the valve element being disposed in a valvechamber defined by the valve insert in the region of the valve seat, andan end, facing away from the valve chamber of the valve element isoperatively connected to an armature, the improvement wherein an endface of the armature, facing toward the valve insert, and/or an end faceof the valve insert, facing toward the end face of the armature, isembodied with a surface profile such that a flow cross section, definedby the end faces, varies at least regionally in the radial directionand/or in the circumferential direction of the armature, wherein the endface of the armature and/or the end face of the valve insert is embodiedwith circular channels extending in the circumferential direction of thearmature and wherein the circular channels are spaced apart from oneanother concentrically in the radial direction.
 2. The valve arrangementaccording to claim 1, wherein the end face of the armature and/or theend face of the valve insert is embodied with at least one channelextending in the radial direction of the armature.
 3. The valvearrangement according to claim 2, wherein an outer circumference of thearmature includes at least one conduit extending in a longitudinaldirection of the armature.
 4. The valve arrangement according to claim1, wherein an outer circumference of the armature includes at least oneconduit extending in a longitudinal direction of the aRMature.